1. Field of the Invention
The present invention relates to a scanning electron microscope and a three-dimensional shape measuring device that used it, and, in particular, relates to a three-dimensional shape measuring device provided with a multiply-segmented backscattered electron detector.
2. Description of the Related Art
There are several conventional techniques available for three-dimensional shape measurement using a scanning electron microscope. The three-dimensional shape measurement techniques include: a method based on a feature point shift of a stereo pair image obtained by causing a sample or an incident electron beam to be inclined; and a method based on the difference among signals detected by multiple detectors arranged uniformly with respect to a sample. A representative example of the latter method is a three-dimensional shape measuring device including a backscattered electron detector, which is arranged in a circular pattern facing a sample, equally-segmented in a radial manner. The device is configured to measure a surface shape of a sample on the basis of the difference among directional detection signals from detection elements respectively provided in the segmented backscattered electron detector (refer to FIG. 1 in Japanese Unexamined Patent Application Publication No. Sho 62-6112 and Japanese Patent Application Publication No. 2002-31520).